Such drive units are fundamentally known and include a stator, an exciter coil and an armature. The stator and the armature are stamp-packed from individual insulated sheet metal layers to prevent eddy currents. The stator is designed to be essentially U-shaped and has a first leg and a second leg, an additional leg being provided between the first leg and the second leg. The exciter coil is designed as a coil for an electromagnet and is usually positioned on the at least one additional leg. The armature is situated across the legs of the stator, lateral air gap sections being provided between the first leg and the armature and between the second leg and the armature, and central air gap sections being provided between the additional leg and the armature. The central air gap sections and the lateral air gap sections run at an inclination relative to a longitudinal axis of the additional leg.
Such a drive unit is known from WO 00/27599 by the present applicant, for example.
One disadvantage with this design is that optimal mechanical performance of the drive unit is not achieved. Another disadvantage is that with such a configuration, the copper consumption for the exciter coil and the stamping waste of the dynamo sheet metal, of which the stator and armature are packed, are relatively high.
Accordingly, it would be desirable to improve upon a known drive unit for a hair cutting machine of the type defined in the introduction so that it will no longer have the disadvantages described. In particular the mechanical performance of the machine is to be improved, while at the same time the copper consumption and the waste of dynamo sheet metal are to be reduced.